00:01Oh, hey, hi!
00:03I'm Chris and Chris, and welcome to So Cool Science.
00:07Science you can do right at home.
00:09I'm just observing the days of the phases of the moon.
00:13And going over today's science file.
00:17In today's science file, it says...
00:20How many days does it take the moon to revolve around the Earth?
00:24Well, that's an awesome question. Try this.
00:34You will need your phone.
00:37Okay, so you probably think you know the answer to this.
00:40But I'm going to prove to you that you don't know Jack.
00:43Or Cindy or Lou and a couple other people too.
00:47Okay, here's what you're going to do.
00:49You're going to wait for the next new moon.
00:51Then you're going to get your phone.
00:53And you're going to snap a picture of the moon.
00:55And you're going to keep snapping a picture of the moon
00:57until he gets back to the new moon.
00:59And check this out.
01:28Now that's so wicked cool.
01:30It only took 27 days.
01:32Now you probably thought it was going to take like 28 or 30.
01:35But it only took 27.
01:36And if we measured this even more scientifically accurate,
01:40it would only take about 29.4.
01:43Okay, so if the moon goes around the Earth in 29 days,
01:47why don't our calendars have 29 days?
01:49And who came up with our calendar anyway?
01:53Well, don't look at me.
01:56Take a closer look at this.
02:00Ancient people noticed that the Earth repeated four seasons.
02:04Winter, spring, summer, and fall.
02:06They also noticed that the moon went through its full phase cycle
02:10three times during each season.
02:12So ancient people multiplied three moon cycles by four seasons
02:16and got a 12 lunar cycle year, or 12 months.
02:20However, since the moon goes around the Earth in 29.4 days,
02:25it's not exactly 12 months.
02:27So sometimes they would have to add an additional month or two
02:30every now and then.
02:31Julius Caesar, a Roman Emperor,
02:33didn't like having to add additional months,
02:36and wanted a calendar based more on the 365 days
02:39it took the Earth to go around the sun.
02:42However, it's not exactly 365 days.
02:46It's more closer to 365 and a quarter day.
02:49So 500 years later, Caesar's calendar was way off.
02:53So Pope Gregory VIII approved a calendar reform,
02:56whereby an extra day would be added every four years.
02:59However, it's not even exactly 365 and a quarter days.
03:04It's just slightly less than that.
03:06So every 300 out of 400 years, we skip a leap year.
03:10The Gregorian calendar isn't perfect,
03:12but right now it's the best calendar for keeping the days
03:15and the months lighting up with the seasons of Earth.
03:18So now you know how our calendar came to be.
03:22You know, observing the moon over a few days
03:26is why science is so cool.
Comments